FIG. 1 illustrates a conventional follower configuration of an operational amplifier. The output Vout of the amplifier is applied directly to the inverting input of the amplifier. The input signal Vp is applied to the non-inverting input of the amplifier.
This configuration may be used to process input signals Vp having large dynamics that can substantially reach the supply rail levels of the amplifier. In this situation the amplifier often reaches its slew-rate, i.e. the maximum dV/dt that the amplifier can produce. An input signal having a steeper slope than the slew-rate produces an output signal having a slope limited to the slew-rate.
Conventional operational amplifier structures have different rise and fall slew-rates. As a result, when the slope of the input signal is greater than the slew-rate, the average level of the output signal shifts noticeably compared to the average level of the input signal. This is not desirable in certain applications.